We plan to continue work on the purification to homogeneity of the corneal low molecular weight antiprotease fraction and to determine its chemical parameters, including amino acid composition; examine its effect at various concentrations on differently treated corneas, especially with respect to collagenolysis; the level of trypsin necessary to produce corneal ulceration in variously extracted and treated corneas, including alkali-burned corneal buttons; isolate the corneal low molecular weight antiprotease from rabbits, and compare its properties to that of the bovine inhibitory factor for enzyme specificity, especially cathepsins, elastin, plasmin, and plasminogen activators. The effect of ascorbic acid, at various dose levels, in the presence and absence of added trace amounts of metal ions (iron and copper) and that of thiol-blocking reagents shall also be studied in corneal ulceration. In addition, we want to investigate the platelet aggregation by corneal collagen, its concentration and time dependence, and if possible, its morphology. Experiments concerning the platelet aggregating ability of collagenase treated corneal collagen, including that of suspension made of corneas with and without activation of collagenase, such as following extraction with 0.5 M NaCl will also be performed.